WASHINGTON--(BUSINESS WIRE)--In dense, urban centers around the world, many people live and work in
dim and narrow streets surrounded by tall buildings that block sunlight.
And as the global population continues to rise and buildings are jammed
closer together, the darkness will only spread.

To alleviate the problem, Egyptian researchers have developed a
corrugated, translucent panel that redirects sunlight onto narrow
streets and alleyways. The panel is mounted on rooftops and hung over
the edge at an angle, where it spreads sunlight onto the street below.
The researchers describe their design in a paper published today in Energy
Express, a supplement of The Optical Society’s (OSA)
open-access journal Optics
Express.

"We expect the device to provide illumination to perform everyday tasks,
and improve the quality of light and health conditions in dark areas,"
said Amr Safwat, a professor of electronics and communications
engineering at Ain Shams University in Cairo, Egypt. These dimly lit
areas specifically include narrow streets in developing countries, but
Safwat said the new panel could be used in any country as a greener,
cheaper, and more pleasant alternative to fluorescent and other
artificial light.

While other commercially available window-like devices can redirect
light, they are designed for shade and redirecting glare or for
brightening a room—not a narrow street. So the researchers decided to
create their own design. They wanted a simple way to redistribute
natural light without the need for a tracking device that follows the
rising and setting sun.

What they came up with is a panel made of polymethyl methacrylate
(PMMA), the same acrylic plastic of which Plexiglas is made. The bottom
of the panel is smooth while the top is covered in ridges that are based
on a sine wave, the mathematical function that describes everything from
light to pendulums. The researchers used computer simulations to find
the size and shape of the grooves that distribute the most amount of
sunlight in a wide range of sun positions all year round, whether it's
high or low in the sky. A sine-wave pattern is also easy to manufacture.

Using simulations of sunlight shining on an alleyway, the researchers
found that their panels increased illumination by 200 percent and 400
percent in autumn and winter, respectively, when sunlight is most
limited. They also tested a small prototype over a
0.4-meter-by-0.4-meter shaft that is 1.2-meters deep and found that it
lit up the area as designed.

The next step, Safwat said, will be to build a full-scale model 10 times
bigger to validate their calculations and to test it in a real alleyway.
The team then plans to market and commercialize the panel. He estimates
that a one-square-meter panel and a frame will cost between $70 and $100.

And that may be a small price to pay for the benefits of sunlight. The
lack of sun in urban areas doesn't just make life gloomy; it can be
harmful to your health, Safwat said.

He also noted that using sunlight to illuminate historical places—such
as ancient alleyways in Egypt—also helps preserve the authenticity of
the site, maintaining its cultural value and historical significance.

This work was funded by the Science and Technology Development Fund of
Egypt.

EDITOR’S NOTE: High-resolution images are available to members of the
media upon request. Contact Angela Stark, astark@osa.org.

About Energy Express

The Optical Society's (OSA) premier open-access journal, Optics
Express, publishes a bimonthly supplement, Energy Express.
This supplement is dedicated to new developments in the science and
engineering of light and their impact on sustainable energy, the
environment, and green technologies. It is led by Editor Christian
Seassal from CNRS, University of Lyon, France and is available at no
cost to readers online at www.OpticsInfoBase.org/EE.

About Optics Express

Optics Express reports on new developments in all fields of
optical science and technology every two weeks. The journal provides
rapid publication of original, peer-reviewed papers. It is published by
The Optical Society and edited by Andrew M. Weiner of Purdue University. Optics
Express is an open-access journal and is available at no cost to
readers online at www.OpticsInfoBase.org/OE.

About OSA

Founded in 1916, The Optical Society (OSA) is the leading professional
society for scientists, engineers, students and business leaders who
fuel discoveries, shape real-world applications and accelerate
achievements in the science of light. Through world-renowned
publications, meetings and membership programs, OSA provides quality
research, inspired interactions and dedicated resources for its
extensive global network of professionals in optics and photonics. For
more information, visit www.osa.org.